There has been some recent discussion of a remark US Secretary of Education Arne Duncan made in June, 2013: "'cultural hesitation'" makes it more difficult for some Hispanic parents to want to enroll their children in public preschool programs because of their preference for family and friends." (http://cnsnews.com/news/article/education-secretary-arne-duncan-pre-school-better-grandma)
Duncan quoted former Secretary of Health and Human Services Kathleen Sebelius as saying that "preschool could make Hispanic children 'culturally comfortable' with entering public schools as kindergartners .... people are scared to put their kids in more formal care and they prefer, you know, to do the grandmother, the neighbor, whatever."
Secretary Duncan's position is not the result of a careful analysis of the impact of preschool, research on"unschooling" (see eg Paula Rothermel's research, http://www.pjrothermel.com/, and Rolstad, K. & Kesson, K. 2013. Journal of Unschooling and Alternative Learning 7, (14)), , the value of discovery learning and following one's own interests, or the value of a strong foundation in the child's first language and home culture. I think that the reason for his position is simple: Fewer children in preschool means fewer tests are given, and this reduces profits for the testing industry.
Preschool is now "academic," filled with academic standards and tests. Every test given, (excuse me, every "assessment") is profit for the .001%. (Eager parents, in fact, can download preschool tests (see e.g. tests available at the oddly named "have fun teaching" website: http://www.havefunteaching.com/worksheets/test-practice/preschool-test-practice. )
The testing includes, of course, admissions tests for some preschools. (One elite preschool even requires genetic testing, a DNA analysis, to determine a child's potential (http://www.npr.org/2012/04/01/149804404/n-y-preschool-starts-dna-testing-for-admission), clear evidence that Alfie Kohn was right when he observed that satire is now obsolete in education.)